Technical Field
This disclosure relates to an image reading device, an image forming apparatus such as a copier, printer, facsimile machine, and a multi-functional apparatus including at least two functions of the copier, printer, and facsimile machine, and incorporating the image reading device, and a method of reading images using the image reading device.
Related Art
In image reading devices such as scanners, density of scanned images changes as time elapses due to changes over time in an amount of light emitted from a light source and in sensitivity of reading elements along with change in temperature. In order to address this inconvenience, shading correction is performed between image reading jobs so that quality of reading images is maintained at a constant level.
For example, when a recording medium is conveyed to an exposure glass of a known image reading device, a rear roller rotates to convey the recording medium to a contact image sensor disposed between the exposure glass and the rear roller.
A white reference sheet disposed above the rear roller is moved with rotation of an arm from a standby position toward a reading position. As the rear roller rotates, the white reference sheet is conveyed between the exposure glass and the rear roller. An image on the white reference sheet is read by the contact image sensor for performing a shading correction.